Time, projects, and invoices for consultancies.
Consultainer tracks the hours your team works for each client and turns them into invoices — on your own server, from a single docker compose file. Open source, no per-seat pricing, no data leaving your network.
Running in a few minutes
Postgres, the app, and a small scheduler for recurring invoices, reminders and syncs — all in one compose file.
- Open it in a browser and create your organization and admin account. No email setup required.
- Sign in with your own identity provider — Authentik, Okta, Entra ID, Keycloak, any OIDC.
- Multi-arch images for amd64 and arm64. Upgrades are
docker compose pull. - Nightly database backups built in, optionally copied to your S3 bucket. The self-hosting guide covers HTTPS, upgrades and restore.
# grab the compose file and example settings curl -O https://raw.githubusercontent.com/Armistice-Group/retainer/main/docker-compose.yml curl -o .env https://raw.githubusercontent.com/Armistice-Group/retainer/main/.env.example # fill in the Required section of .env, then docker compose up -d
What it does
Built for engineering, security, and design consultancies billing by the hour, flat fee, or milestone.
Track time against real work
Log hours by hand, run a timer on any task, or turn your calendar's meetings into time — each with a suggested project. See your week at a glance, or the whole team's, with optional weekly approval.
Projects that know their budget
Per-person bill rates, hour budgets that alert you at 80%, tasks synced both ways with Linear, milestones, and expenses — with invoiced-to-date and profit always in view.
Invoices from unbilled work, or a set amount
Pull unbilled time, completed milestones, and expenses into an invoice in a few clicks, or bill a set fee or deposit. Email clients a link to view and pay it, with the PDF and timesheet attached if they want them — and know when they open it. Take payment through Stripe or Mercury, push to QuickBooks.
Billing on a schedule
Put a client on a weekly, bi-weekly, or monthly cycle and their invoice drafts itself. Retainers bill a fixed amount on their own schedule, and overdue reminders go out on their own.
A month at a small consultancy
Northwind Labs is made up: four people, five clients, a mix of hourly, flat-fee and retainer work. Here's how a month of it goes in Consultainer. Every screen is the real app on the demo data that ships in the repo, so you can load it and click around yourself.
Email in two minutes, from the browser
Maya, the owner, picks Resend or any SMTP server (Postmark, SES, Google Workspace…), pastes the settings and sends herself a test, or a sample of the invoice email clients get. No config files, no restart.
Bill the deposit before any work is logged
Atlas Robotics signs phase 2. Maya bills 50% up front: one line, $9,000, a note saying what it covers. Ticked as a deposit, the payment becomes Atlas's credit for the phase 2 invoices.
Their accounts team wants the PDF and a timesheet
Atlas's AP team files PDFs and checks hours. Maya attaches the PDF and includes the timesheet: every entry's date, start and end time, who did it and what. Ken still gets the link to pay online.
What Atlas sees when they open it
No login: the invoice, how to pay, and the timesheet, with any screenshots the team marked as evidence. Maya sees under Activity that Ken opened the email, the page and the PDF.
Log time from your phone
Sam, a contractor, installs the phone app from Chrome, starts a timer on Fleet Dashboard, and shares a screenshot straight into a time entry as evidence.
See where the month landed
Hours, invoiced, received and outstanding, utilization by person and profit by project, with each table a CSV away, for Maya's monthly review.
Works with your agent, too
A REST API and a built-in MCP server let Claude, Cursor, or any agent log time and draft invoices with a personal API key — the same permissions as the person it acts for.